Hey everyone. I just recently finished all of Companion quests. I was wondering if the Glenmoril witches, that we need to kill for their heads, respawn?

I'm asking this because I killed them all in that cave of theirs (I forget the name of it) but I only picked up one of their heads for Koldak. I decided to keep the werewolf disease a little longer and I'm wondering if somewhere down the road, if I decide to cure it, I can go back there and get what I need for a cure or If the witches can be found somewhere else in skyrim and I can collect a head from those as well.

Thanks in advance!

I killed them all and had to go back much later on a book quest and they were all still dead and headless[I took all the heads] so I am almost 100% sure they do not come back.